1. Field of the Invention
The invention relates to a lockable piston-cylinder assembly, in particular a gas-pressure spring or a damper with a cylinder arrangement having a closed cylinder in which a piston dividing the cylinder into a first and a second chamber is guided movably, and a piston rod leading out of the cylinder interior is sealed at one end face of the cylinder. A locking tube surrounding the cylinder arrangement has a first end section pivotably mounted at the free end of the piston rod for pivoting between a release position coaxial to the piston rod for and a locking position inclined towards the axis of the piston rod, and a second end section with a supporting stop such that the locking tube can be pivoted into the locking position when the piston rod is extended.
2. Description of the Related Art
With a gas-pressure spring of this type that is used for example for opening of hatches or doors, in particular on motor vehicles, it is known that the locking tube is permanently loaded toward its inclined locking position by a spring. When the piston rod extends, the locking tube thus slides with its end section opposite the free end of the piston rod at one end along the cylinder until, after overriding the cylinder end, it pivots into the locking position. In this position, part of the opening of the locking tube is opposite the corresponding end face of the cylinder and forms a stop which the end of the locking tube contacts and prevents any further retraction of the piston rod.
Only after a manual of the locking tube can the piston rod retract back into the cylinder.
This gas-pressure spring has the disadvantage that with every extension of the piston rod beyond a certain extension length, a locking always occurs automatically that then has to be released manually.